Radioactive Decontamination Research Articles

Neighbourhood Sum-Based Structural Analysis for Sodalite System

Background: Sodalite is a type of zeolite with an intricate structure comprising a system of interrelated cages and tunnels. It is extensively used in sieving applications due to its unique structure and properties. As a result, it finds several uses in water and air purifica-tion, radioactive decontamination, detergents, and so on. Due to the potential positive envi-ronmental impact of sodalite materials, analysing the molecule at a structural level becomes the need of the hour. Methods: Molecular descriptors form the basis of many convenient and cost-effective tech-niques for studying molecular structures. In this article, the neighbourhood sum-based de-scriptors are computed edge-partition techniques, simplifying the intricate structures with cages and tunnels into more simple graphs for mathematical convenience. Results: This article presents the calculated analytical expressions for molecular descriptors, specifically focusing on various neighbourhood sum degree-based indices in sodalite struc-tures. Conclusion: The results presented in this article establish the dependence of the physical properties of a molecule on its underlying structure using the computed molecular de-scriptors. The graphical comparison of the results provides a visual representation of the be-haviour of indices with respect to the molecular structure.

Synthesis and evaluation of radioactive decontamination efficiency of carboxylic 4-tert-butylcalix[6]arene derivative with decontamination solution

ABSTRACT Scientists have recently conducted thorough investigations on tert-butylcalix[6]arene and its derivatives owing to their ability to form complexes with radioactive elements for applications in radioactive decontamination. Current research presents the result of synthesising compounds 1,3,5-trimethoxy-2,4,6-tri (carboxylic acid)-4-tert-butylcalix[6]arene and evaluates the influence of this compound on the decontamination efficiency of a new skin decontamination (SD) kit developed by Lequidon laboratory. Decontamination effectiveness for short-lived radionuclides: metal (134Cs) and non-metallic (131I) determined by in vivo method. Adding 1% of 4-tert-butyl calix[6]arene derivative significantly enhanced the efficiency of the radioactive decontamination solution (SD).

Tough strippable hydrogel films based on acrylic acid/acrylamide/zirconyl chloride for surface radioactive decontamination at low temperatures

Strippable films are extensively utilised for the decontamination of radioactive surfaces because of their cost-effectiveness, ease of operation, and minimal liquid waste. However, traditional strippable detergents are formulated for use at normal ambient temperatures and typically lose their efficacy at low temperatures because of poor performance or excessively long film-forming time. In this study, we have developed an anti-freezing and sprayable AMZW detergent based on acrylic acid (AA), acrylamide (AM), zirconyl chloride octahydrate (ZrOCl2·8H2O), and water (H2O), which possesses a freezing point of approximately −34 ℃ due to the solvation interaction between Zr4+ and H2O. Even at temperatures as low as −25 ℃, the AMZW detergent can be easily sprayed using a conventional apparatus and rapidly cured into a strippable hydrogel film under irradiation by 365 nm UV LED light (LED@365 nm), household LED panel light, or sunlight. The coordination bond formed between Zr4+ and the carboxyl group of the polymer chain imparts excellent mechanical properties to the hydrogel while the carboxyl group can complex with uranyl nitrate hexahydrate (UO2(NO3)2·6H2O)—a radioactive simulant. As a result, the strippable hydrogel film demonstrates high tensile strength (6.1 ∼ 19.3 MPa), excellent flexibility (elongation of 90 ∼ 855 %), moderate peel strength (0.05 ∼ 3 N/cm, room temperature (RT)), and high decontamination efficiency (>91.6 % on stainless steel and glass; >81.3 % on concrete) over a wide range of temperatures (−25 ∼ 25 ℃). This work presents a novel approach for producing anti-freezing, fast-forming, flexible, and high-strength strippable hydrogel films for surface radioactive decontamination at low temperatures.

Rheological and radioactive decontamination properties of ethyl cellulose sols in green solvents at a temperature below 0 °C.

Strippable film decontamination has been considered one of the best prospects for radioactive surface decontamination due to its high decontamination effect and less secondary pollution. However, research into strippable films has until now focused on radioactive decontamination at room temperature. Therefore, it is vital to seek a suitable degradable material for preparing strippable films in removing contaminants in an extremely cold region, as it will face the problem of the freezing of the detergent. Ethyl cellulose (EC) is a kind of degradable biopolymer which is easily dissolved in volatile green organic solvents to form a sol below 0 °C which is advantageous for forming a film. Therefore, it would be the best choice for preparing a strippable film detergent. In this study, EC sols were obtained by placing EC powder into the green solvents anhydrous ethanol and ethyl acetate. The steady and dynamic rheological behavior of EC sols was investigated with a rotary rheometer with the temperature ranging from -10 °C to 0 °C to disclose their spraying performance. Moreover, the radioactive decontamination effect of EC sols and the mechanism were also investigated. The results showed that the EC sols were pseudoplastic fluids which obeyed the Ostwald-de Waele power law below 0 °C. Furthermore, the viscosity of EC sols could be reduced by stirring, which is convenient for large-area spraying during decontamination below 0 °C. At -10 °C, the comprehensive decontamination rates of all plates were over 85%. Therefore, EC sols could be used as a basic material for strippable film decontamination below 0 °C.

Preparation and performance study of the self-embrittle composite coatings for radioactive decontamination of surface layer of various materials

Preparation and performance study of the self-embrittle composite coatings for radioactive decontamination of surface layer of various materials

Modeling and optimization of the self-embrittle corrosive bifunctional detergent for corrosive deep decontamination of stainless steel surface by RAFT one-pot method based on machine learning and response surface methodology

Nuclear facilities generate lots of contaminated stainless steel metallic material during maintenance and decommissioning. As a new radioactive decontamination method, the self-embrittle decontamination method has the advantage of less secondary contaminants and being able to operate machinery remotely. Adding a certain amount of corrosive components to the self-embrittle compound detergent can achieve the dual functions of self-embrittlement and corrosive decontamination. It was used to optimized the response surface methodology (RSM) and train and evaluate four different machine learning models by the recorded data set. The purpose of the analysis was to quantify the accuracy of the corrosion decontamination effect of RSM model and four types of machine learning model. The results exhibits that the long short-term memory neural network (LSTM) model performs well. The prepared detergent can achieve the average corrosion depth of 5.9454 μm on stainless steel, which can satisfy the corrosion decontamination of radioactively contaminated stainless steel surfaces.

Preparation and Performance of a Self-Brittle Corrosive Bifunctional Detergent for Corrosive Deep Decontamination of Stainless Steel Surface Based on Controlled Polymerization by the RAFT One-Pot Method

Nuclear facilities generate large amounts of contaminated stainless steel metallic material during maintenance and decommissioning. As a new radioactive decontamination method, the self-brittle decontamination method has the advantages of fewer secondary contaminants and can be operated remotely mechanically. The addition of a certain amount of corrosive components to the self-brittlement composite decontaminant can achieve the dual function of self-brittlement and corrosion decontamination. The performance of the decontaminant was investigated by single-factor experiments using electrochemical tests, morphological observations, and weight loss tests. The results show that the decontaminant has good self-embrittlement. When the concentration of HCl is 2.50 mol/L, HNO3 is 3.50 mol/L, NaCl is 0.10 mol/L, and FeCl3 is 0.15 mol/L, the decontaminant is formulated to have the best corrosion and decontamination effect on stainless steel. The detergent will produce a uniform corrosion layer on the surface of stainless steel, and the average corrosion depth can reach 8.3268 μm.

Preparation and properties of visible light-cured strippable film for radioactive decontamination

In this research, solutions of styrene-butadiene-styrene block copolymer (SBS) in 2-ethoxyethyl methacrylate (EOEMA) were used to prepare strippable films via rapid visible-light curing, where the mixture of camphorquinone (CQ), diphenylsilane (DPS) and diphenyliodonium hexafluorophosphate (Iod) was employed as the photoinitiating system, LED@405 nm, sunlight or household LED panel light as the light source and no any solvent was involved. The double bond conversion for pure EOEMA under LED@405 nm was firstly monitored by real-time FTIR and it reached 72% within 300 s. The rapid-curing of SBS/EOEMA solutions were systematically investigated and it was found that the solution with 16 wt% SBS became completely dried at the presence of 2.16 mol% crosslinker and 3.6 wt% photoinitiating system after 240 s irradiation under LED@405 nm. The tensile strength, elongation at break and glass transition temperature of the resultant strippable film were determined to be about 4.4 ± 0.5 MPa, 130 ± 11.2% and 6.9 °C, respectively, by mechanical properties testing and DSC measurements. Also, the decontamination efficiencies (DE) of household LED panel light/sunlight cured-strippable film for uranium nitrate on stainless steel, glass, and ceramic surface were evaluated to be higher than 90%. These results indicate that this rapid-curing strippable films would be a good candidate material for large-scale radioactive decontamination.

Preparation and performance study of the self-brittle composite detergent with controllable morphology for radioactive decontamination of surface layer of various materials by RAFT one-pot synthesis

Reversible deactivated radical polymerization (RDRP) has obvious advantages in the synthesis of block copolymers with well-defined structure and composition, but it has some defects in practical applications. An amphiphilic block copolymer (PMAA-co-PTFEMA)-b-PMMA-b-(PMAA-co-PTFEMA) with the self-brittle function was prepared by the reversible addition-fragmentation chain transfer polymerization (RAFT) one-pot method using S, S-dibenzyl trithiocarbonate (DBTTC) as the chain transfer agent, methyl methacrylate (MMA) as the first monomer, methacrylic acid (MAA) as the second monomer, and trifluoroethyl methacrylate (TFEMA) as the modified component. Then it was grafted onto the surface of the modified nano-silica with KH570-modified nano-silica after high-speed shearing, and a self-brittle composite detergent that can be used for radioactive decontamination of surface layers of various materials was prepared by controlling the morphology of the nano-silica. By observing the detergent with different monomer ratios, it can be seen that the control of the self-brittlement morphology of the detergent can be achieved by adjusting the ratio of MMA/MAA, which lays the foundation for future practical applications.

Preparation of high tensile strength modified cellulose-based strippable coating and its application on radioactive decontamination at low-temperature

Preparation of high tensile strength modified cellulose-based strippable coating and its application on radioactive decontamination at low-temperature

Current state and the concept of a modern platform for chemical, biological and radioactive decontamination

The paper addresses decontamination as a system of troop protection in the event of a risk of contamination in functional and task terms. It presents the analysis of technical equipment and decontamination procedures in the Polish Armed Forces and NATO. The concept of a modern platform for liquidation of chemical, biological and radioactive contamination has been described.

Radioactive Decontamination using Bamboo Activated Carbon for Healthy Environment in Nuclear Medicine

Radioactive wastes by products excreted from radioiodine (RAI) therapy patient waste such as urine, faeces, sweat and puke might risk to radiation contamination if not systematically manage. These wastes can affect human health and environment, thus sustain and systematic management must be strictly considered. In addition, radiopharmaceutical preparations in nuclear medicine risk to radioactive spillage by chances. In this study, new sustainable adsorption technique by using agriculture product was proposed to decontaminate the possibilities of radioactive spillage in RAI therapy where different concentrations of bamboo activated carbon (BAC) was mixed with pure 131I and filtered by using filter paper. Radioactivity for each filtered sample (sediment) was measured using dose calibrator to determine kinetic reactions of adsorbed radioactive substances. The data shows the sediment radioactivity was increased with increased of BAC concentrations. The radioactivity loss after filtration was 76.1% (50 mg/ml), 76.3% (100 mg/ml), 83.5% (150 mg/ml), 80.4% (200 mg/ml), 85% (250 mg/ml) and 68% (control) due to high agglomeration between BAC and 131I. Mixtures with highest BAC concentration was then characterized using FESEM and EDX for morphology and elemental analysis. FESEM image proved there were porous structures on the BAC to attract 131I and other molecules. EDX revealed that 131I and other elements were attracted to BAC layered sheets. This study revealed that BAC performed different capabilities as an adsorbent material under different experimental conditions and has high potential for sustainable radionuclide decontamination agents especially for RAI therapy in ensuring continuous healthy environment for staff, patients and public in Nuclear Medicine Department.

Effects of Fatty Alcohols with Different Chain Lengths on the Performance of Low pH Biomass-Based Foams for Radioactive Decontamination.

Compared with polymers and nanoparticles, fatty alcohols can not only increase the stability of foam, but also maintain better foamability at pH < 2, which is beneficial to reduce waste liquid and increase decontamination efficiency for radioactive surface pollution. However, different fatty alcohols have different hydrophobic chain lengths. The effects of fatty alcohols with different chain lengths on the performance of decontamination foam were studied at pH < 2, to assist in the selection of suitable fatty alcohols as foam stabilizers. Combined with betaine surfactant and phytic acid, biomass-based foams were synthesized using fatty alcohols with different chain lengths. When the hydrophobic tail groups of the fatty alcohol and the surfactant were the same, the foam showed the best performance, including the lowest surface tension, the highest liquid film strength, the greatest sag-resistance and the best stability. However, when the hydrophobic tail groups were different, the space between adjacent surface active molecules was increased by thermal motion of the excess terminal tail segments (a tail-wagging effect), and the adsorption density reduced on the gas-liquid interface, leading to increased surface tension and decreased liquid film strength, sag-resistance and stability. The use of decontamination foam stabilized by fatty alcohols with the same hydrophobic group as the surfactant was found to increase the decontamination rate of radioactive uranium pollution from 64 to over 90% on a vertical surface.

Radioactive decontamination in low-temperature environments by using a novel high-strength strippable coating

Accidents involving nuclear leakage and radioactive source diffusion will result in a substantial amount of radioactive pollution, posing a threat to the world's environment as well as human safety. To get rid of the pollution, this work describes a new type of strippable detergent coating designed to remove radioactive contamination, especially in low-temperature conditions. In situ polymerization was employed to make EC/PUA/PVAc detergent from degradable ethyl cellulose (EC), tea polyphenols (TP), and polyvinyl acetate (PVAc), and polytetramethylene ether glycol bis-para-aminobenzoate (P1000). The film-forming performance, decontamination efficiency, and mechanical properties of the decontamination coating formed by the detergent were studied. Designed to work in a low-temperature environment, the detergent can be sprayed and peeled to remove surface radioactive staining. A universal material testing machine was used to assess the low-temperature rheometry, SEM, EDX, FT-IR, and other variables and to characterize the decontamination coating and the decontamination mechanism of the detergent. At -10–10 °C, the EC/PUA/PVAc detergent has good fluidity and sprayability and forms a strippable coating. The tensile strength of the decontamination coating can be as high as 26.4 MPa, and its 180° peel strength on ceramic tile, glass, stainless steel, cement, marble are 0.49 ± 0.08 N/m, 1.82 ± 0.41 N/m, 3.03 ± 1.65 N/m, 35.60 ± 1.17 N/m, 44.43 ± 4.10 N/m, respectively. The decontamination factors ranged from 3.32 to 10.02, with a decontamination rate above 85%.

Removable coatings: Thermal stability and decontamination of steel surfaces from 241Am.

This study presents a comparative analysis of several commercial removable materials for radioactive decontamination of steel surfaces using 241Am as representative radionuclide. The selection criteria of removable coatings for this study included a history of application, commercial availability, easy handling conditions and different composition and formulation. Carbon steel and stainless steel coupons were utilized as common industrial materials, and the experimental series were expanded to include the rusting treatment of these surfaces as it is common for decommissioned nuclear facilities. Radionuclide 241Am was deposited on the coupon surfaces and used to evaluate decontamination efficiency of the removable coatings, which were pre-screened for the ease of application and removal from the surface. Selected coatings were characterized with Fourier-transform infrared spectroscopy and thermogravimetric analysis, decontamination efficiencies for different types of steel surfaces, and potential enhancement of the removal efficiencies of the select removable coatings via amendment with EDTA. Across all the coatings, decontamination efficiencies for stainless steel (both pristine and with oxidizing treatment) were higher than for pristine carbon steel, which in turn were higher than for rusted carbon steel. Amendment with EDTA improved removal efficiency of a removable coating. CC Strip coating exhibited easy handling and high decontamination efficiency, (up to 97% when EDTA-amended), but its drying time was the longest, and thermal analysis indicated higher release of energy during thermal decomposition compared to the other coatings. Hydrogel-based DeconGel coating, even though not the easiest in handling among the rest of materials, exhibited high decontamination efficiency, efficient drying at the ambient temperature leading to the loss of about 80wt% due to solvent evaporation, and extremely low heat released during thermal decomposition; therefore, it is considered a preferable choice for the considered factors.

Accumulation of lead radionuclides in 18 leaf vegetable types in Viet Nam

Studying the concentration of radioactive lead in soil and plants, and using plants for phytoremediation are important for the environment and human health protection. In this study, we used gamma spectrometry to determine activity concentration in soil - plants, transfer factor. The average activity concentration of lead radionuclides in soil and plants were in the following order of 210Pb > 214Pb > 212Pb. The average activity ratio of 214Pb and 212Pb to 210Pb in soil were 0.70 and 0.59 and in plants were 0.69 and 0.14, respectively. The results showed that there was not much difference between the ratio of radioactive 214Pb and 210Pb concentrations in vegetable and plant samples. Ming aralia (Polyscias fruticose) and lettuce (Lactuca sativa) contained the highest concentrations of 210Pb, and Malabar spinach (Basella alba) contained the lowest concentration. Ming aralia could be used for the radioactive decontamination of 210Pb. There vegetable samples from Ho Chi Minh City were considered safe for human consumption in the aspect of lead radionuclides.

A State-of-the-Art Review of Radioactive Decontamination Technologies: Facing the Upcoming Wave of Decommissioning and Dismantling of Nuclear Facilities

The average share of nuclear energy in electricity production is expected to increase under the background of the global pursuit towards carbon neutrality. Conjugating with its rapid development, the wave of decommissioning and dismantling (D&amp;D) of nuclear facilities is coming. The surface decontamination is a prerequisite to D&amp;D, which will make it easier and reduce the volume of radioactive wastes. However, there are no comprehensive studies on the decontamination methods, which is not helpful for the sustainable development of nuclear energy and environment protection. Therefore, in this work, the current status and future trends of global energy and nuclear energy are first analyzed. Then, various decontamination approaches are comparatively studied, including cleaning mechanisms, application subjects, and intrinsic advantages and disadvantages. Finally, the criteria and factors for selecting a decontamination process, the challenges, and future studies are directed. Among the mechanical methods, laser-based cleaning is high-speed, having automation ability, and thus is promising, although it creates a dust and airborne contaminant hazard. In further studies, factors such as selecting a proper laser facility, optimizing operating parameters, and designing a high-efficiency dust collection system could be studied. Regarding the chemical method, chemical gels are good for decontaminating complex shapes and vertical and overhead surfaces. In addition, they can enhance other decon agents’ efficiency by improving contact time. However, the formulation of colloidal gels is complex and no gel type is useful for all contaminants. Therefore, novel and versatile gels need be developed to enlarge their application field. Combining various decontamination methods will often have better results and thus a reasonable and effective combination of these decontamination methods has become the main direction.

A Sprayable and Visible Light Rapid-Cured Strippable Film for Surface Radioactive Decontamination.

Strippable film is effective for removing radioactive contamination. However, it still has some limitations, such as the long curing time (about 30 min~24 h) and the requirement of organic solvents. To address these issues, we report a simple protocol to prepare strippable decontamination films using liquid polybutadiene (LPB) and tert-butyl acrylate (TBA) as the raw materials without solvent and using camphorquinone/ethyl 4-dimethylaminobenzoate (CQ/EDB) as a photoinitiator, where the film was formed under household LED panel light or daylight irradiation for about 540 s. After a thorough study of viscosity, real-time Fourier transform infrared (RT-FTIR spectra), gel and volatile organic compound (VOC) contents, mechanical properties and decontamination efficiency, the optimum composition and curing conditions were determined for the decontamination strippable film. VOC content is as low as 12.7 ± 0.7% and the resultant strippable film exhibits good mechanical performances with a tensile strength of up to 5.4 ± 0.4 MPa and elongation of up to 66.6 ± 13%. Most important, the decontamination efficiencies of this strippable film for 133CsCl on glass, ceramic and metal surfaces reach up to 98.1%, 94.3% and 97.6%, respectively.

Radioactive decontamination of metal surfaces using peelable films made from chitosan gels and chitosan/magnetite nanoparticle composites

In this work, we explored the feasibility of using peelable films from chitosan gels and chitosan/magnetite nanoparticle (NPs–Fe3O4) composites to deal with radioactive contamination on metallic surfaces. We formulated four chitosan-based gels, one without NPs–Fe3O4 and three with NPs–Fe3O4: one using commercial nanoparticles and the other two synthesized by applying the chemical reduction method at 25 °C and 94 °C. The decontamination capacity of these gels was evaluated on steel stainless and aluminum, clean and corroded, and on weathered iron test pieces. The films of chitosan-based gels were characterized by infrared spectroscopy. The radioactive decontamination process from metal surfaces was most efficient on clean surfaces. The decontamination factors were independent of the presence of NPs–Fe3O4 in the chitosan-based gel applied to the metal surface and depended on the type of radioisotope deposited on the metal. Gels formulated with 2.8% w/v chitosan in 1 M acetic acid with and without NPs–Fe3O4 (333 μg/mL) were applied to a non-compactable waste contaminated with uranium, which obtained removal efficiencies of 85%.

Simulations and Experimental Verifications of an Algorithm for Radiation Source Mapping and Navigational Path Generation.

Accurate and efficient mapping and localization of both ionizing and non-ionizing radiation sources are important across many different fields. As such, a versatile mapping and navigational path generation algorithm, which can be applied to any point source measurements that follow an inverse-square characteristic, was developed using non-linear least squares methods. Forty thousand simulations were performed on the algorithm, which located sources successfully in a 10 m × 10 m × 10 m three-dimensional space with a success rate of over 80% across different noise functions, given a proportional constant of 10 to 1,000. The algorithm was also verified experimentally with small-scale radioactive decontamination of a 70 cm × 70 cm surface and localization of a lost Wi-Fi router in a 70 m × 70 m open field. One hundred twenty-one measurements were taken from each experiment, which were then fed into the algorithm for navigation. For the radioactive 137Cs source, the estimated locations were within 7 cm × 7 cm of the answer in 79.3% of the scenarios, while the Wi-Fi router was located to within 7 m × 7 m in 57.9% of the tests. In general, the method requires much less information and data than a geographically comprehensive survey and thus shows a lot of potential for practical applications, such as lost source retrieval with unmanned aerial vehicles, small-scale decontamination, mapping undocumented Wi-Fi routers or radio towers, and radiation simulation with radio signals. Different failure modes, desirable features, and potential improvements were also identified but remain as future work.